This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bacteriophage Syn 5 infects Synechococcus, a cyanobacterium that plays an important role in the Carbon and Oxygen cycles on Earth. As such it is of interest to ecologists and oceanographers, who are just realizing the importance of oceanic bacteria and their parasites. We are interested in the structural adaptations that they have made to their environment.